Methane hydrate exists as a solid substance in layers that contain sand and other sediment. Hydrate to methane gas and water must be accomplished in order to produce the methane gas. The production of methane hydrate means dissociating methane hydrate in the layers and collecting the resultant methane gas through wells and production systems. To dissociate methane hydrate that is stable at low temperature and under high pressure, there must be an (1) increase the temperature, (2) decrease the pressure, (3) or both. The optimum methane hydrate production method is one based on the “depressurization method.” However, since methane hydrate layers are unconsolidated sediments, sand production occurs with the methane gas and water. Because removal of the methane, water, and sand, wellbore stability becomes an issue that cannot be overcome with conventional sand control methodologies. Economical and effective measures for preventing sand production and solving borehole stability issues require a novel approach to completion methodology.
The proposed method to control sand production and provide better borehole stability comprises providing a shape memory polymer foam filter that does not depend on the borehole for containment for sand management. The shape memory polymer will be utilized such that a flow path would not be exposed that would permit the production of sand from the borehole. One other issue related to the depressurization method of methane hydrate production is the uniform application of a differential pressure across the reservoir interface. The method further comprises a porous media under the shaped memory polymer foam filter that can be varied in number and permeability to balance the differential pressure applied to the reservoir being produced. This improves borehole stability via uniform drawdown and flow from the exposed reservoir. While these techniques could be used in a conventional open hole or cased hole completion, it is desirable to under ream or expand the borehole size to help increase wellbore radius and decrease flow velocities at the sand management/reservoir interface. Additionally, consolidated proppant or sand could be deposited adjacent the shape memory foam as it is not the objective to fully occupy the borehole with the foam after it crosses its critical temperature. Instead, in recognition that the hole can be enlarged with initial reaming to reduce fluid velocities or alternatively additional methane production destabilizes the formation and can enlarge the borehole, the consolidated proppant or sand can be an outer protective layer to the foam. Its ability to self-adhere contains the foam and protects the foam from erosive velocity effects of the produced methane.
Several references that employ memory foam in sand control applications are as follows:    WO/2011/162895A;    U.S. Pat. No. 8,353,346    US20110252781    WO/2011/133319A2    US20130062067    WO/2013/036446A1    US20130126170    U.S. Pat. No. 8,048,348    US20100089565    US20110162780    U.S. Pat. No. 7,926,565    WO/2010/045077A2    US20110067872    WO/2011/037950A2    U.S. Pat. No. 7,832,490    US20080296023    US20080296020    U.S. Pat. No. 7,743,835    WO/2008/151311A3
Flow balancing devices are generally discussed in the following references:    U.S. Pat. No. 7,954,546    U.S. Pat. No. 7,578,343    U.S. Pat. No. 8,225,863    U.S. Pat. No. 7,413,022    U.S. Pat. No. 7,921,915
A need exists for an assembly and method of producing methane from an unconsolidated formation surrounding a borehole having methane hydrate, sand or other sediments. Once positioned and set near the formation, the filtration assembly should be able to manage sand and other sediments without having to rely on the geometric configuration of the borehole for containment, such that should the surrounding borehole subsequently enlarge or the space between the formation and the assembly increase due to changing reservoir conditions the geometric configuration of the assembly will not substantially change.
Those skilled in the art will better appreciate additional aspects of the invention from a review of the detailed description of the preferred embodiment and the associated drawings while appreciating that the full scope of the invention is to be determined by the appended claims.